Method of preparing 2-imino-oxazolidines and the stabilization of polyesters therewith

ABSTRACT

THIS INVENTION RELATES TO 2-IMINO-OXAZOLIDINES, METHODS OF PREPARATION AND TO THE STABILIZATION OF ESTER-CONTAINING COMPOSITIONS AGAINST HYDROLYSIS.

United States Patent 3,594,387 METHOD OF PREPARING Z-llVIINO-OXAZOLI- DINES AND THE STABILIZATION OF POLY- ESTERS THEREWITH Sidney H. Metzger, New Martinsville, W. Va., assignor to Mobay Chemical Company, Pittsburgh, Pa. N Drawing. Filed Oct. 9, 1964, Ser. No. 402,951 Int. Cl. C0711 85/26, 95/00 US. Cl. 260-307 8 Claims ABSTRACT OF THE DISCLOSURE This invention relates to 2-imino-oxazolidines, methods of preparation and to the stabilization of ester-containing compositions against hydrolysis.

It has been heretofore recognized in an article entitled Anlagerungsreaktionen Mit Epoxyden by Klaus Gulbins and Karl Hamann, Berichte, volume 94, page .3287 (1961) that the reaction of an epoxide or an alkylene carbonate with a carbodiimide should be expected to result in the formation of oxazolidines. This article however, points out that this is not the case; the irninooxazolidines do not result because of being unstable and are converted immediately to cyclic ureas.

It is an object of this invention to provide new Z-iminooxazolidines. It is another object of this invention to provide a method of preparing Z-imino-oxazolidines. It is another object of this invention to provide poly-Z-iminooxazolidines. It is another object of this invention to provide specific reaction conditions which prevent the immediate conversion of 2-imino-oxazolidines to cyclic ureas. It is still another object of this invention to provide a method of stabilizing ester containing compositions against hydrolysis. It is a further object of this invention to provide a method of stabilizing polyesters against hydrolysis. It is another object of this invention to provide polyesters stabilized against hydrolysis.

The foregoing objects and others which will become apparent from the following description are accomplished in accordance with the invention, generally speaking, by providing 2-imino-oxazolidines having the formula wherein Z is a radical obtained by removing at least one NCO group from an organic isocyanate, n is an integer equal to the number of NCO groups removed from Z, R is an aryl, alkyl or cycloalkyl radical and R is hydrogen or the residue remaining after removal of the 1,2-epoxide group or 1,2-carbonate group from a 1,2-epoxide or 1,2 carbonate respectively. When Z is a monovalent radical, it can be aryl, alkyl or cycloalkyl and may be the same or difl erent from R. A method of preparation of the compounds shown in the formula above when Z is monovalent is to react an organic carbodiimide With either a 1,2-epoxide or a 1,2-alkylene carbonate at a temperature less than 220 C. for a period of time less than 3 hours in an inert solvent. When this method of preparation is used, Z and R are the same as the organic radical of the carbodiimide and R is hydrogen orthe residue remaining after removal of the 1,2-epoxide or 1,2-carbonate from a 1,2-epoxide or a 1,2-carbonate respectively. Thus, R is hydrogen when either ethylene oxide or ethylene carbonate is used in the reaction with the carbodiimide and methyl when either 1,2-propylene oxide or 1,2-propylene carbonate is used. R also represents the radical remaining after removal of the 1,2-epoxide group or 1,2-

3,594,387 Patented July 20, 1971 carbonate group from any suitable epoxide or carbonate such as, for example, 1,2-butylene carbonate, 1,2-octylene carbonate, 1,2-octadecylene carbonate, 1,2-butylene oxide, 1,2-amylene oxide, 1,2-octylene oxide, 1,2-octadecylene oxide, 3-ethyl 1,2 pentylene oxide, styrene oxide, phenyl glycidyl ether, allyl glycidyl ether, octadecyl glycidyl ether, amyl glycidyl ether, tolyl glycidy ether, chlorophenyl glycidyl ether, naphthyl glycidyl ether and the like.

2 and R may be the same or different in the same molecule depending upon the particular carbodiimide used as the starting compound, such as, for example, aryl such as phenyl, ix-naphthyl, ,B-naphthyl, wanthryl, fl-anthryl, gamma-anthryl; o-tolyl, m-tolyl, p-tolyl, 2,3-xylyl, 2,4- xylyl, 2,5-xylyl, 2,6-xylyl, 3,4-xylyl, 3,5-xylyl, o-cumenyl, m-curnenyl, p-cumenyl, mesityl, o-ethylphenyl, m-ethylphenyl, p-ethylphenyl, 0-, mand p-tertiary butylphenyl, 2,6-ditertiary butylphenyl, o-, mand p-ethoxyphenyl, o-, mand p-tert. butoxyphenyl and the like. Alkyl, such as, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, n-pentyl and various positional isomers thereof, such as, for example, l-methyl-butyl, 2- methyl-butyl, 3-methyl-butyl, 1,1 dimethylpropyl, 1,2- dimethylpropyl, 2,2 dimethylpropyl, 1 ethylpropyl and the like; corresponding straight and branched chain isomers of hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nondecyl, eicosyl and the like; cycloalkyl such as, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, 0-, mand p-isopropyl cyclohexyl, o-, mand p tert. butyl cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl, cyclododecyl, cyclotridecyl, cyclotetradecyl, cyclopentadecyl, cyclohexadecyl, cycloheptadecyl, cyclooctadecyl, cyclonondecyl, cycloeicosyl and the like.

In the preparation of the 2-imino-oxazolidines as represented by the formula above when Z is monovalent, it is essential that the reaction between the epoxide or carbonate and the carbodiimide be conducted in an inert solvent. While it is not essential, it is highly preferred that a suitable catalyst be used in carrying out this invention and that the reaction be maintained at a temperature less than 220 C. for a period of time less than three hours.

In practicing the invention, any suitable basic catalyst may be used to prepare imino-oxazolidines where Z is monovalent such as, for example, tertiary amines including N,N dimethylaniline, 1 methyl-4-(dimethyl amino ethyl)piperazine, N-ethyl ethenylidine, N,N,N',N-tetramethyl ethylene diamine, triethyl amine, 2,4,6-tri(dimethyl amino methyDphenyl, N-ethyl morpholine, Z-methyl piperizine and the like; alkali metal hydroxides including sodium hydroxide, potassium hydroxide, lithium hydroxide and the like; tetramethyl ammonium bromide, tetraethyl ammonium bromide and the like. It is preferred that the tetraalkyl ammonium bromide catalysts be used.

Any suitable carbodiimide may be used in the practice of this invention to prepare Z-imino-oxazolidines such as, for example,

diisopropyl carbodiimide,

dicyclohexyl carbodiimide,

methyl tertiary-butyl carbodiimide,

tertiary butyl phenyl carbodiimide,

tetramethylene-bis-diisobutyl carbodiimide,

N-dirnethyl amino propyl tertiary butyl carbodiimide,

the monoglycol ether of hydroxyphenyl-tertiary butyl carbodiimides,

diphenyl carbodiimide,

dinaphthyl carbodiimide,

2,2'-dimethyl-diphenyl carbodiimide,

2,2-diisopropyl-diphenyl carbodiimide,

2-dodeeyl-2'-n-propyl-diphenyl carbodiimide, 2,2'-diethoxy-diphenyl carbodiimide. 2-dodecyl-2'-ethyl-diphenyl carbodiimide, 2,2'-dichloro-diphenyl carbodiirnide, 2,2'-ditolyl-diphenyl carbodiimide. 2,2'-dibenzyl-diphenyl carbodiimide, 2,2-dinitrodiphenyl carbodiimide, 2-ethyl-2'-isopropyl-diphenyl carbodiimide. 2,6,2,6'-tetraethyl-diphenyl carbodiimide, 2,6,2',6'-tetrasecondary-butyl-diphenyl carbodiimide. 2,6,2,6'-tetraethyl-3,3-dichlorodiphenyl carbodiimide. 2,6,2',6-tetraisopropyl-3,3-dinitro-diphenyl carbodiimide, 2ethyl-cyclohexyLZ-isopropyl-phenyl carbodiimide. 2,4,6,2,4',6-hexaisopropyldiphenyl carbodiimide. 2,2-diethyl-dicyclohexyl carbodiimide. 2,6,2,6'-tetraisopropyl-dicyclohexyl carbodiimide, 2,6,2,6-tetraisopropyl dicyclohexyl carbodiimide, 2,6,2,6'-tetraethyl-dicyclohexyl carbodiimide and 2,2'-dichloro-dicyclohexyl carbodiimide, 2,2-diearbethoxy diphenyl carbodiimide. 2,2'-dicyano-diphenyl carbodiimide and the like.

Any suitable carbodiimide having more than one carbodiimide group may also be used such as those described in US. Patent 2,941,966.

Any suitable inert solvent can be used as the medium in which the reaction is conducted such as, for example, dioxane, heptane, toluene, benzene, tetrahydroturan, dimethylformamide, dimethylacetamide, dialkylcellosolves, dialkylcarbitols and the like.

In the preparation of the I-imino-oxazolidines the epoxide or carbonate is used in equivalent proportions or in excess of the quantity of the carbodiimide used. The materials are inserted into a reaction vessel which contains a suitable solvent medium. The reaction vessel is heated to a temperature of from about 200 to about 220 C. where it is maintained for about one to about three hours. The reaction mass is then cooled and the product is separated by standard techniques such as crystallization or distillation. If desired, a suitable catalyst is also added to the reaction vessel.

The compounds having the formula set forth above can be prepared by an interchange reaction whereby a different organic radical is substituted for Z. This is accom plished by reacting an organic isocyanate with a Z-iminooxazolidine. This reaction takes place in accordance with the following general equation:

RNCO ZN:CNR RN=CNR ZNCO 0 CIIHZ t lHz x CH RI An equilibrium is established and in order to drive the reaction to the right, the isocyanate formed, that is, ZNCO is removed substantially as soon as it is formed. This can be accomplished by distillation.

When polyisocyanates are used, the interchange reaction will take place at one or more of the NCO groups present of the polyisocyanate depending upon the amount of the 2-iminooxazolidine present in the reaction mixture. The polyimino-oxazolidines may also be used and can be prepared by this same technique. In the interchange reaction, the materials are heated to a temperature of from about 50 C. to about 220 C. at either atmospheric pressure or in a partial vacuum. The isocyanate formed is substantially immediately removed from the reaction mixture by a suitable arranged distillation column.

Any suitable organic isocyanate can be used in the interchange reaction with the mono or poly 2-imino-oxazolidines such as, for example,

tetramethylene diisocyanate, hexamethylene diisocyanate, 1,4-phenylene diisocyanate, 1,3-phenylene diisocyanate,

1,4-cyclohexylene diisocyanate,

2.4-tolylene diisocyanate,

2,5-tolylene diisocyanate,

2.6-tolylene diisocyanate,

3 .S-tolylene diisocyanate,

4-chloro- 1,3-phenylene diisocyanate,

l-methoxy-L-l-phenylene diisocyanate,

l'methyl-3,5-diethyl-2,6-phenylene diisocyanate,

1.3,S-triethyLZA-phenylene diisocyanate,

l-methyl-3.5'diethyl-Z,4-phenylene diisocyanate,

l -meth,1-3.S-diethyl-6-chlor0-2,4-phenylene diisocyanate,

6-methyl-2,4-diethyl-5-nitro-1,3-phenylene diisocyanate,

pxylylene diisocyanate,

tn-xylylene diisocyanate,

4.6dimethyll ,3-xylylene diisocyanate,

l.3-dimethyl-4,6-bis(,9-isocyanatoethyl)benzene,

3-t'a-isocyanatoethyl)phenylisocyanate,

1-methyl-2,4-cyclohexylene diisocyanate,

4.4'-biphenylene diisocyanate,

3,3'-dimethyl-4,4'-biphenylene diisocyanate,

3 ,3'-dimethoxy-4,4-biphenylene diisocyanate,

3 3'-diethoxy-4,4'-biphenylene diisocyanate,

1,1'-bis-(4-isocyanatophenyl)cyclohexane,

4,4-diisocyanatodiphenylether,

4,4-diisocyanato-dicycylohexylmethane,

4.4-diisocyanato-diphenylmethane,

4.4'-diisocyanato-3,3-dimethyldiphenylmethane,

4.4'diisocyanato 3,3-dichlorodiphenylmethane,

4.4-diisocyanato-diphenyl-dimethylmethane,

l,5-naphthylene diisocyanate,

4.4-4"-triisocyanato-triphenylmethane,

2.4,4-triisocyanato-diphenylether,

2.4,6-triisocyanato l-methyl-3,S-diethylbenzene,

o,o,o-tris( l-isocyanatophenyl)phosphorothioate and the like;

methyl isocyanate,

ethyl isocyanate,

propyl isocyanate,

isopropyl isocyanate,

allyl isocyanate,

butyl isocyanate,

isobutyl isocyanate,

see-butyl isocyanate,

tert.-butyl isocyanate,

amyl isocyanate,

3methoxypropyl isocyanate, tetradecyl isocyanate,

chlorodecyl isocyanate, 4-oxa-hexadecyl isocyanate, 4-oxa-6-butyldodecyl isocyanate, dodecyl isocyanate,

hexadecyl isocyanate,

octadecyl isocyanate, 1-isocyanato-octadecene-9,

phenyl isocyanate,

cyclohexyl isocyanate, o-chloorphenyl isocyanate, m-chloorphenyl isocyanate, p-chlorophenyl isocyanate,

o-toluyl isocyanate,

m-toluyl isocyanate,

p-toluyl isocyanate,

o-ethylphenyl isocyanate, o-ethoxyphenyl isocyanate, p-ethoxyphenyl isocyanate, o-nitrophenyl isocyanate, m-nitrophenyl isocyanate, p-nitrophenyl isocyanate, 1-isocyanato-3-benzalacetophenone, l-isocyanatosulfonyl-4-methylbenzene, benzyl isocyanate, m-isocyanato-cinnamic-acidethylester, 2,4-dichlorophenyl isocyanate, 3,4-di-chlorophenyl isocyanate,

2,5-dichlorophenyl isocyanate,

a-naphthyl isocyanate,

p-naphthyl isocyanate,

-hydroxy-u-naphthyl isocyanate, 5-isocyanato-a-naphthylchloroformate, o-biphenyl isocyanate,

o-phenoxyphenyl isocyanate, 3-nitro-4-chlorophenyl isocyanate, and the like.

The 2-imino-oxazolidines are particularly useful in the stabilization of ester containing compositions. In the event that the ester or polyester is used in further reactions with other compounds such as, for example, the reaction with an organic polyisocyanate to prepare polyurethanes, the Z-imino-oxazolidines can also be added after this reaction takes place. The addition can be made with the oxazolidines in the dissolved state by rolling, milling, stirring or any suitable technique.

Any composition containing ester linkages may be stabilized against hydrolytic degradation in accordance with this invention such as, for example, the reaction product of a carboxylic acid with an alcohol. Any suitable carboxylic acid may be used in the preparation of compositions containing ester groups in accordance with this invention such as, for example, acetic acid, propionic acid, phenylacetic acid, benzoyl acetic acid, pyruvic acid, propionyl acetic acid, butyrl formic acid, aceto butyric acid, levulinic acid, 1,2-keto stearic acid, 1,3-keto behenic acid, aldovaleric acid, hexahydrobenzoic acid, 1,2-cyclohexanone carboxylic acid, brassylic acid, phenylmalonic acid, ethylglycollic acid, thiodiglycollic acid, ,B-chloropropionic acid, glutacom'c acid, ethoxymalonic acid, malic acid, aspartic acid, acrylic acid, methacrylic acid, cinnarnic acid, benzene tricarboxylic acid, adipic acid, succinic acid, suberic acid, sebacic acid, oxalic acid, methyladipic acid, glutaric acid, pimelic acid, azelaic acid, phthalic acid, terephthalic acid, isophthalic acid, thiodipropionic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid and the like.

my suitable alcohol may be used in the preparation of esters such as, for example, methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, secondary butyl alcohol, tertiary butyl alcohol, amyl alcohol, hexyl alcohol, octyl alcohol, decyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, allyl alcohol, methallyl alcohol, crotyl alcohol, 2-propyn-l-ol, oleyl alcohol, geranoil, citronellol, linalool, diacetone alcohol, ethylene glycol monoethyl ether, cyclohexanol, naphthenic alcohols, benzyl alcohol, tolyl alcohol, phenylethyl alcohol, octadecylbenzyl alcohol, ethylene glycol, propylene glycol, 1,4-butanediol, 1,3- butanediol, 1,5-pentanediol, 1,6-hexanediol, bis-(hydroxy methyl cyclohexane), di-ethylene glycol, 2,2-dimethyl propylene glycol, 1,3,6-hexanetriol, trimethylol propane, pentaerythritol, sorbitol, glycerine and the like. The method of stabilizing compositions containing ester groups is applicable not only to polyesters in accordance with the compounds listed above having a functionality greater than 1. For example, where any of the dior polycarboxylic acids are reacted with the dior polyhydric alcohols, a polyester having more than one ester group, of course, will result.

Of course, other compositions containing polyester resins as a reaction component or in admixture can also be stabilized by the process of this invention. For example, compositions such as polyester amides and polyester urethanes can be stabilized. The reaction product of any of the carboxy terminated or hydroxyl terminated esters set forth above can be reacted with a suitable isocyanate to prepare a polyurethane. In the preparation of polyesteramides, the reaction of a carboxylic acid, an alcohol and an amine can be carried out simultaneously or in steps in the manner set forth for the preparation of polyesteramides. Of course, aminoalcohols and aminoacids can be used in the preparation of polyesteramides. The pertinent feature is, however, that any composition containing ester groups can be stabilized against hydrolysis by the introduction thereof of an oxazolidine within the formula set forth above.

Any suitable organic polyisocyanate may be used to prepare polyester urethanes which may be stabilized in accordance with this invention such as, for example, those more particularly set forth above.

Any suitable amino compound can be used to prepare polyesteramides such as, for example, hexamethylene diamine, ethylene diamine, propylene diamine, butylene diamine, cyclohexylene diamine, phenylene diamine, tolylene diamine, xylylene diamine, 4,4'-diamino-diphenylmethane, naphthylene diamine, aminoethyl alcohol, aminopropyl alcohol, aminobutyl alcohol, aminobenzyl alcohol, aminoacetic acid, aminopropionic acid, aminobutyric acid, aminovaleric acid, aminophthalic acid, aminobenzoic acid and the like. Of course, the amino compounds may be reacted either simultaneously with the ester forming components or sequentially therewith.

It is also within the scope of the invention that naturally occurring esters may be stabilized against hydrolysis and aging in accordance with this invention such as, for example, castor oil, cocoanut oil, corn oil, cottonseed oil, horse fat oil, lard oil, wool fat, japan wax, mutton tallow, beef tallow, neats foot oil, palm oil, peanut oil, carnauba wax, spermaceti, beeswax, rapeseed oil, soya bean oil, whale oil, sperm oil and the like. Further, any compositions containing ester groups as well as unsaturation may be stabilized in accordance with this invention. Such compositions may be formed by polymerization, condensation or a combination of both. Any of those unsaturated carboxylic acids mentioned above may be used in the preparation of such polyesters. Further examples of such compositions include polyester resins of polymerizable monomers and unsaturated polyesters, for example, those of fumaric or maleic acid as well as ethylene vinyl ester copolymers, acrylic and methacrylic acid ester polymers and their copolymers with vinyl esters, fluorinated acrylic esters and their copolymers, copolymers of acrylonitrile and acrylic acid esters such as methylacrylate and the like. The invention is particularly applicable to the stabilization of polyesters used in the manufacture of synthetic resins which may result in the form of lacquers, foils and coatings, fibers, foam materials, elastomers or casting resins for molded elements.

Any of the Z-imino-oxazolidines within the generic formula set forth above may be used to stabilize any of the polyester compositions set forth. The oxazolidines should be used in a stabilizing amount, however, it is preferred that from about 0.1 to about 10 parts per 100 parts of a polyester be used.

The oxazolidines may be incorporated into the polyester by any suitable technique which includes dry blending, dissolving in the polyester itself, dissolving in a co-reactant before reaction with the polyester and the like.

The invention is further illustrated but not limited by the following examples in which parts are by weight unless otherwise specified.

EXAMPLE 1 Preparation of 3-phenyl-2-phenylimino oxazolidines To a one-liter stirred autoclave is charged about 145.0 parts (0.75 mol) of diphenyl-carbodiimide, a solution of about 53.1 parts (1.2 mols) of ethylene oxide in about 250 parts by volume of dry dioxane and about 3.0 parts of tetraethylammonium bromide. The mixture is heated with stirring at about 200 to about 212 C. for approximately minutes. A pressure drop of about 40 p.s.i.

is observed. After cooling, a total of 130.0 parts of solid is recovered from the dioxane solution. The 3-phenyl-2- phenylimino oxazolidine is separated by fractional crystallization and melts at 115 C. The infrared spectrum of the oxazolidine shows a strong absorbence of 1205 cm.- characteristic of the C stretch which is not present in the spectrum of the cyclic urea.

Oxazolidine AnaIysis.Calculated (percent): C, 75.61; H, 5.88; N, 11.76. Found (percent): C, 75.98; H, 5.86; N, 11.66.

EXAMPLE 2 To a one-liter stirred autoclave is charged about 145.2 parts (0.75 mol) of diphenylcarbodiimide, about 75.0 parts (1.3 mol) of propylene oxide, about 300 parts by volume of dioxane and about 3.00 parts of tetraethylammonium bromide. The reaction mixture is stirred at about ZOO-204 C. for about one. hour and 15 minutes. After cooling, excess propylene oxide and dioxane are removed by stripping in vacuo, leaving about 163 parts of a brown oil as residue. Unreacted carbodiimide is removed by dispersing the sludge in boiling hexane and removing the carbodiimide as a solution in the hexane layer. The infrared spectrum of the semi-solid clearly shows the -C':N-, CH of alkyl and CO- vibrations of the 2-phenylimin0-3-phenyl-5-methyloxazolidine.

EXAMPLE 3 To a one-liter stirred autoclave is added about 70.5 parts (0.25 mol) of bis(4-ethoxyphenyl)carbodiimide, about 1.02 parts of tetraethylammonium bromide and about 250 parts by volume of dioxane. The autoclave is purged with nitrogen and then about 21.5 parts (0.489 mol) of ethylene oxide is pressured in. The reaction is conducted at about 190 to about 208 C. for approximately 135 minutes. A pressure drop of 35-40 p.s.i. is observed. Upon cooling, 36.3 parts of solid (plates) crystallizes. After stripping the dioxane from the remaining solution 57.2 parts of solid is left. From this dark solid by repeated recrystallizations from isopropanol, there is obtained the desired oxazolidine of the following structure:

Stabilization of a polyester About 1 part of the product of Example 1 is dissolved in about 100 parts of a hydroxyl polyester having a molecular weight of about 2000 and an hydroxy number of about 57 which is prepared by reacting adipic acid with diethylene glycol and trimethylol propane. About 10 parts of an isomeric mixture of 80% 2,4- and 20% 2,6-tolylene diisocyanate is stirred into this mixture and this reaction mixture is then cast onto a Teflon coated tray to a thickness of about inch where it is permitted to remain for about 2 hours at about 110 C.

Identical samples are prepared without the addition of the product of Example 1. Samples having the additive and those without the additive are placed on a wire screen over a steam bath at 100 C. The unmodified samples soften after 72 hours and completely failed after 105 hours. Those containing the additive in accordance with this invention do not soften until 144 hours of exposure.

EXAMPLE 5 To about 150 parts of the polyester of Example 4 are added 1.35 parts of a compound having the formula About 100 parts of this mixture are reacted with about 10 parts of an isomeric mixture of 80% 2,4- and 20% 2,6-tolylene diisocyanate. The reaction mixture, which is one typically used in the preparation of printing rollers, is cast into a test sample. The test sample is subjected to saturated steam at 100 C. This sample failed after 144 hours. In comparison, a similar sample containing none of the additive set forth above failed after 96 hours.

EXAMPLE 6 The procedure of Example 5 is followed with the exception that 4.05 parts of the compound having the formula represented are added to the polyester in place of the 1.35 parts of Example 5. The test sample prepared using this stabilized polyester exhibits no signs of failure even after 144 hours on a steam bath.

EXAMPLE 7 Preparation of:

CH z II To a boiling flask equipped with a thermometer and a distillation head is charged about 11.9 parts (0.05 mol) of 3-phenyl-2-phenylimino-oxazolidine and about 6.3 parts (0.025 mol) of 4,4-diisocyanatodiphenylmethane. The mixture is heated to from about to about 127 C. at about 6.0 mm. Hg vacuum, during which time a low boiling liquid distills and is collected. After about 15 minutes heating, the reaction mixture solidifies and traps some lowboiling liquid beneath the solid mass. The reaction is completed by heating the solid mass to from about 127 to about 145 C. while gradually lowering the pressure until about 1 mm. Hg is reached. The collected distillate weighs about 4.0 parts and is shown to be pure phenylisocyanate. The residual solid is recrystallized from dioxane to remove trapped phenylisocyanate. Weight of recrystallized white solid is about 10.4 parts M.P. 216- 18 C. The infrared spectrum, with absorbancies at 1675 cm." (C=N) and 1205 cm.- (CO), definitely identifies the product as 1.

EXAMPLE 8 Preparation of In a 3-necked flask equipped with a thermometer and mechanical stirrer, and to which is attached a 10 inch heated distillation column packed with glass helices is charged about 47.6 parts (0.2 mol) of 3-phenyl-2-phenylimino-oxazolidine, about 25.0 parts (0.1 mol) of 4,4'-diisocyanatodiphenylmethane and about 100 parts by volume of decalin (dried over sodium). The solution is heated to boiling in vacuo and the pressure is gradually raised to continually increase the boiling temperature. Initial conditions are about C. at about 15 mm. Hg; final conditions are about 126 C. above mm. Hg. Total reaction time is about three hours. Phenylisocyanate, along with decalin, is continually removed as it is formed. As the reaction progresses, Compound I begins to crystallize. At the conclusion of the reaction, the white solid is removed by filtration, washed with petroleum ether and 7 9 dried. Weight of product is about 45.5 parts or 93.2% of theory. The crude solid melts at 212-218" C.

EXAMPLE 9 Preparation of I (3H2 xcfin: N the \m, N

oils out and solidifies upon cooling. It is broken up and filtered giving an almost quantitative yield of II.

EXAMPLE 10 Preparation of:

III

The product (II) from Example 8 is put into Decalin and heated approximately two hours at from about 145 to about 150 0. Compound 'I'II oils out and solidifies upon cooling. Recrystallization from acetone gives a light tan solid M.P. 178-80 C. The infrared spectrum of the product (III) showed a doublet of about equal intensities at 1710 cmr (C=O of urea) and 16-75 cm.- (C=N of imino-oxazolidine), CO stretch at 1205 cm.- and ali- 10 a plate and then the solidified material is subjected to saturated steam at about 0. for the time indicated in the table.

Hours to EXAMPLE 12 The procedure of Example 4 is followed with the exception that a compound indicated in the following table is added to the polyester in the amounts set forth. The casting in each case is then subjected to saturated steam at 100 C. until failure. The compounds added have the general formula: v

The values for R, R and R" are indicated in the table in order to specifically identify the compounds used.

To about 100 parts of an hydroxyl terminated polyester prepared by reacting 10 mols of adipic acid and 11 mols of 1,4-butanediol to an hydroxy number of 56 and an acid number less than one are added 9 parts of 1,4-butanediol and about 40 parts of 4,4'-diphenylmethane diisocyanate. The reaction mixture is immediately cast onto a heated plate maintained at a temperature of about C. where it is permitted to solidify. Upon solidification, the material is removed from the plate and tested for elongation, elongation set, tensile and tear strength. The sample is then subjected to steam at 15 lbs/sq. inch gauge for a period of 16 hours and then, the samples are again tested. To each of three 100 parts samples of the polyester reacted as above, are added the quantities of compound I of Example 7 indicated in the attached table. The test data both before and after the steam test are set forth.

Parts/100 parts Elongation Elongation set Tensile Tear polyester Before After Before After Before After Before After phatic CN at 1230 cm.-' typical of the CN in imidazolidinones.

EXAMPLE 11 To about 100 parts of the polyester of Example 4 are 70 added the amounts of the compounds indicated in the accompanying table. This mixture is then reacted with 10 parts of an isomeric mixture of 80% 2,4- and 20% 2,6-tolylene diisocyanate to prepare a typical printing roller formulation. The reaction mixture is then cast onto 75 siderable detail in the foregoing for the purpose of illus- 1 l tration, it is to be understood that such detail is solely for this purpose and that variations can be made by those skilled in the art without departing from the spirit and scope of the invention except as is set forth in the claims.

What is claimed is:

1. A method of preparing 2-imino-oxazolidines which comprises reacting in an inert solvent an organic carbodiimide with a member selected from the group consisting of a 1,2-epoxide and a 1,2-alkylene carbonate, said reaction being conducted at a temperature less than 220 C. for a period of time less than 3 hours.

2. The process of claim 1 wherein said reaction is conducted at a temperature of from about 200 to less than 220 C.

3. The process of claim 1 wherein said reaction is conducted in the presence of a basic catalyst.

4. The process of claim 3 wherein the catalyst is a tetraalkyl ammonium bromide.

5. The process of claim 1 wherein the reaction is conducted in the presence of a catalytic amount of triethyl amine.

6. The compound having the formula 7. The compound having the formula References Cited ALEX MAZEL, Primar Examiner 0 B. I. DENTZ, Assistant Examiner US. Cl. X.R. 

